1801.] 
Letters and Arts of Paris, by Citizen 
Bouvyer pes Mortiers, that an in i- 
vidual, whofe name is not mentioned, had 
made for fale, a pretty large quantity 
of blue for painting, with a mixture of 
cerufe, Pruffian-blue, and oil of walnuts. 
He covered it up with water feveral inches 
to prevent its deficcation, and laid it by till 
occafion fhould require it. After a cer- 
tain time, fome one calling on him 
in want of this paint, he was very much 
furprifed to find it all white, except the 
furface, thecolour of which was well pre- 
ferved. He was inclined to put fome Pruf- 
fian blue into the paint, when, by grinding 
or mixing it in the open air without addi- 
tion, he faw the colour come again of itfelf, 
and in effect, by this operation he reftored 
it to its formerintenfity. He then covered 
it again with oil, imagining that it would 
keep better than under water. But his 
expectation was difappointed, as the co- 
lour difappeared a fecond time, throughout 
the whole mafs. The Society of Medi- 
cine and Arts at Nantes, to which fome of 
this dilcoloured and very white paint was 
brought, caufed fome to be ftretched on 
white paper, upon wood, and on the wall 
of a cafement, and in a fpace of time 
longer or fhorter, the colour appeared 
again in its luftre ; that of the white: pa- 
per was the floweft in its regeneration. 
Here Citizen Lt Bouvyver inquires what 
is the caufe of this phenomenon? Is it 
the oil, which, by changing, difcolours 
the Pruffian-blue? Is it the air in mafs, 
or fome one of its principal conftituents, 
or any other fubftance found to be mingled 
or diffolved in it, which recalls the colour ? 
To thefe queftions the author of the paper 
attempts to reply, by publifhing the dif- 
ferent interefting experiments which he 
has made on this fubjeét, and from which. 
he deduces the following refults: 1. That 
the difcolouration of the paint is not owing 
to the decompofition of the oil, but to the 
change of furfaces occafioned by the re- 
treat of the matter upon itfelf, and by the 
extinction of the luminous globules in the 
{mall laminz and in the pores of the co- 
louring fubftance: 2. That neither the air 
in mafs nor any of its conftituent princi- 
ples, nor any thing contained in it, iS 
neceflary to regenerate the colour, fince~ 
it is regenerated as well in vacuo as 
in theopen air: 3. That caloric, with- 
out the contact of light, impedes the 
return of the colour, inftead of ,contribut- 
ing to it, and even deftroys it: And, 
laftly, that the interior movement of the 
parts, in whatever manner it be excited, 
and the a¢tion of the light, are fufficient 
Montuiy Mag. No. 77: 
Literary and Philofophical Intelligence, 
‘P@HaussouL, HENRIETTE 
145 
to re-produce the colour more or lefs ra- 
pidly, according as there.is more or leis of 
light and of movement. 
Cit. BERNARD prefented tothe fame af- 
fembly the copy and demonfiration of a 
machine of his own invention, by the help 
of which a man deprived of one hand may 
cut a pen. 
Citizen GEOFFROY, of the National In- 
ftitute of Egypt, has in his poffeffion 
three mummies, extremely well preferved. 
They have been taken from the fubterra- 
nean refearches made at Sakkara, andare 
the firft that have been found entire fince 
the arrival of the French in Egypt. Each 
is inclofed in a coffer of fycamore-wood, 
which is itfelf inclofed in feveral folds of 
linen wrapper, glued together ; two of the 
cofters are {culptured, the third is without 
ornaments in relievo, and the wrapper of 
this laft is covered with hieroglyphics. 
In another mummy the hieroglyphics are 
defigned on the wooden coffer which is 
tapeftried with fine pointed linen, and 
the outer fold of linen is only covered 
with infignificant paintings, which, how- 
ever, have preferved all their luftre and 
frefhnefs. Citizen Geoffroy propofes to 
depofit his mummies, as likewife the 
great collection of which they make a 
part, in the Mufeum of Natural Hiftory 
and Antiquities of Pariss The profeffor, 
it is added, {pares neither care nor ex- 
pence, to procure and preferve objects, the 
acquifition of which may.be ufeful to the 
progrefs of Natural Hiftory. 
We learn that the feveral departments 
of the Bibliothéque Frangoife, a periodical, 
critical work, conducted by CHARLES 
PouGeEns, are filled by the following emi- 
nent perfons: Natural Hiftory, Chemiftry, 
and Surgery, by BERTHOLLET, DEsMa- 
RETS, LaBILLARDIERE, Lassus, Mem- 
bers of the Inflitute; Forrin,d’UrsBan, 
&c. Political and Rural Economy, by 
TessizER, of the Infitute, Legiflation, &c. 
DELAMALLE, Jurifconfulte ; P. Usrery. 
Hiftory, Antiquities, and Travels, by 
LanGuLes, Laporté-DUTHEIL, LEeE- 
BLOND, E. TouLonGeon, Members of 
the Inftitute; CHaRDON LA ROCHETTE, 
P. H. Marron, &c. Philofophy, Lite-— 
rature, Poetry, Romances, &c.: by Boure 
FLERS, SEGUR; Mefdames BaauFORT, 
Bourpi£. 
VioT, Louise St. LEoN, HELEN Maria 
WILLIAMS, &c. 
The following is a general and compas 
rative refult of the bills of mortality of 
Cairo, during the years VIT. and VIII. of 
the new French zra, prefented to the Na- 
U tional 
